Some people are calling it ‘mobilegeddon’, others are calling it ‘mobile-pocalypse’, but no matter what you call it, Google’s Mobile Algorithm update, slated for April 21, is purported to be the biggest, most significant algorithm update to date. Industry experts predict that some 15-20% of mobile queries will be affected, and many speculate that even desktop rankings will suffer as a result.

By arming yourself with the information we’ve been able to obtain ahead of launch, you can position your web properties to be fully prepared for Google’s changes.

Mobile Friendliness is no Longer an Option

Google has been slowly moving towards this eventual reality for a long time, but most digital marketers did not expect them to draw such a clear and abrupt line in the sand. With this new update, sites that are not optimized for mobile will be actively penalized in mobile results, and webmasters can expect to see fringe falloff in desktop results as well.

How To Prepare for Google’s Mobile Algorithm Update Now

As with most Google updates, we won’t be able to assess the full impact until the change has been made. However, there are a few key points that we are certain of now:

The algorithm rollout begins April 21st, though it will take 3-7 days to be reflected globally.

There is no longer a sliding scale ranking system for mobile-friendliness. Your site either is or isn’t, there is no longer a middle ground.

Google’s Mobile-Friendliness Testing Tool in action.

You can check whether your site passes Google’s mobile-friendly requirements right now by checking for a ‘Mobile-Friendly‘ label next to your SERP entries. If you’d prefer to check on a page-by-page basis, check the mobile-friendly testing tool, which should match the live Google search results. We discourage the use of mobile usability reports in Google Webmaster Tools, as they can be delayed based on crawl time.

Mobile-Friendliness Will Update in Real Time

At SMX West, Google’s own Gary Illyes fleshed out some more details about the operational mechanics of the algorithm change, which gives some better insight on how webmasters will be able to rebound from ranking losses caused by the update.

You can check mobile-friendliness right in SERP results by looking for the ‘Mobile-friendly’ tag next to results descriptions.

Illyes explained that the algorithm runs and scrapes in real time, so that in theory, you will experience organic performance increases the minute your site becomes mobile-friendly and Google has a chance to crawl it. This should ease some concerns about the ability for sites that previously ranked extremely well to adapt to the new algorithm without seeing a permanent hit to SERP performance.

The Mobile Algorithm is Page-by-Page, not Sitewide

Illyes also clarified how the algorithm will treat sites that may be mostly mobile-optimized, yet still have a handful of assets that are not. Because the algorithm assigns value at the page-level, you will only see a performance hit on those pages that aren’t optimized. If you have a site with 20 pages, 5 of which are not mobile-friendly, you’ll still be able to rank and benefit from the update for the 15 pages that are ready to go. For webmasters that maintain e-commerce sites, or other properties with high page count and specialized content, they can breathe easy knowing that being less than 100% mobile-friendly won’t be an organic search death sentence.

The Short List: What Should You Be Doing To Prepare?

If you’re just looking for the CliffNotes version, here’s what you absolutely need to know:

Your first priority should be to make your website mobile-friendly as soon as possible. A responsive design is best, both from a usability standpoint, and from Google’s point of view.

Begin monitoring your site analytics with a fine-toothed comb starting now. By giving yourself a deep understanding of how your site performs and behaves in organic search now, you will be able to better mitigate any negative performance changes after the flip is switched on April 21st.